The treatment of hyperprolactinaemia is complicated as it depends on the cause and the severity.
When the cause of the hyperprolactinaemia is due to the dopamine antagonistic effects of drugs such as the antipsychotics, there is little indication to treat the hyperprolactinaemia. In these situations, any drug treatment to lower the prolactin levels is likely to antagonise the antipsychotic drugs.
When the cause of the hyperprolactinaemia is due to a macroadenoma, the treatment of choice is a dopamine agonist drug, such as bromocriptine. The main problem with these ergot-related drugs is that they are associated with unpleasant side-effects such as nausea and dizziness. There are now some non-ergot related drugs available (such as cabergoline) which are associated with fewer side-effects. These drugs are able to successfully lower the prolactin levels, but they rarely reduce the tumour size. If these drugs are taken, then they often needed to be taken for life to maintain normal levels of prolactin.
Some specialist centres use radiotherapy to the tumour, but this technique is associated with risks such as optic nerve damage, brain necrosis and late development of hypopituitarism. Because of these risks, radiotherapy is often only used post-surgically with a residual tumour.
Macroprolactinomas that are insensitive to medical therapy require neurosurgical intervention. As it is often very difficult to remove the whole tumour, post-surgical radiotherapy is required.
It has now been reported that upto 10% of tumours spontaneously regress either due to infarction or to the continued drug therapy. These finding mean that many patients have their drug therapy halted for a trial period every few years to avoid needless therapy.
The treatment of choice for microadenomas is dopamine agonist therapy. Surgery is indicated in a sub-group of patients who are have a drug intolerance. In these situations, transnasal or transsphenoidal removal of the microadenoma is performed. In specialist hands this operation produces very beneficial results with minimal interference in remaining pituitary function. Details of the surgery are found in the surgery section.
A special situation that can occur in the treatment of prolactinomas is pregnancy. Prolactinomas tend to increase in size during pregnancy, due to the high levels of circulating oestrogens and the increased blood flow to the pituitary. The drug therapy (dopamine agonists) is usually discontinued in the presence of microadenomas to reduce any risk to the foetus, but continued in the presence of macroadenomas. The reason that the therapy is halted in microadenomas and not macroadenomas is that the smaller adenomas are unlikely to significantly increase in size, whereas the macroadenomas may enlarge and require urgent neurosurgery.